Sherlock Has No Gag Reflex (and John can't get over it)
by wendymarlowe
Summary: John learns that Sherlock has no gag reflex. At all. He tries desperately to ignore the train of thought this revelation leads to, but Sherlock deduces well enough for the both of them. And doesn't mind practical demonstrations. (Warning for a particularly gross crime scene and John vomiting. And Sherlock NOT vomiting, as it so happens.)
1. Chapter 1

The smell was revolting. The bodies hadn't been found for nearly two weeks, in a small office in an un-air-conditioned warehouse in the height of the worst heat wave London had seen in years. What had once been a rather handsome trio of paid escorts (two male, one female) was now reduced to mostly liquids and three soggy skeletons. The stench of decay was apparent even from the parking lot, but inside the warehouse it was inescapable.

John wasn't immune. Despite his medical training, despite his time in the army, he had a rather violent physiological reaction to the smell just the same as Lestrade, Donovan, Anderson, and the other unfortunates assigned to the scene. Someone had thoughtfully set up a box full of plastic bags just outside the warehouse door, with a rubbish bin conveniently located just around the corner. John dashed back out to the parking lot, chest heaving, and grabbed one of the bags from Sherlock's helpfully extended hand.

"Rather interesting case, John - more interesting than I anticipated," Sherlock observed calmly as John voided the contents of his stomach. "Did you notice the staining pattern around the woman's ankles?"

John spat the last remnants of vomit into the bag and glared at Sherlock. "How is it you're not puking up your lunch like the rest of us? Hell, _Anderson_ even lost it, and he's been around plenty more bodies than I have."

"This is hardly the worst crime scene I've seen," Sherlock said.

"I'm not talking about the sight, I'm talking about the _smell_," John snapped. "Surely you noticed?"

Sherlock shrugged. "Obviously. But I don't vomit. Never have."

John blinked and stared at him. "Never?"

"Not that I can recall. Comes from having no gag reflex."

"But what happens when you're sick? Haven't you ever had food poisoning?"

"Twice, but I just suffered through it both times. Honestly, John, it's not that big a deal. Can we get back to the case, or are you going to vomit more?"

John tied off the neck of the bag and tossed it in the rubbish bin. "I - _Christ_, Sherlock. That's not normal, you know that?"

Sherlock shrugged again. "It's hardly the only reason I've been accused of being inhuman." His lips twisted into a smirk. "Besides, it has its uses."

John swallowed against another wave of - something - churning inside him. _Surely he didn't mean_ - but no, this was _Sherlock_, and he'd do well to remember that. John took a deep breath (carefully through his mouth, not his nose), and nodded. "Right, then. Murder victims. What was it about ankles?"

* * *

The ride home in the cab was nearly as bad. John's nose had eventually acclimated to the smell (mostly) while at the scene, but then everyone seemed inclined to move to the far side of the parking lot to hear Sherlock's deductions. And when John and Sherlock climbed into the enclosed back seat of the taxi to go home, it became immediately obvious that 1) they both stank of decomposition, and 2) John's nose wasn't that acclimated after all. It wasn't just his imagination, either - the cabbie was very definitely giving them both a dirty look.

"I need a shower," John muttered.

"Try the soap in the left-hand cupboard over the sink," Sherlock suggested. "It's the most effective at removing biological contaminants."

John looked up. "Would have been nice to know that when I first moved in, you know - I could have been cleaning the fridge with it this whole time."

"Nonsense - it's really not the kind of thing you want near food."

"And yet you think it's safe for skin?"

Sherlock steepled his fingers under his chin. "Have you ever really thought about smells, John? Unlike sight and sound, smells actually _have_ to degrade over time because perceiving them uses them up. In order for you to smell a decomposing body, there literally must be tiny bits of decomposing body floating around in the air and then you breathe them in through your nose and mouth until they meet your olfactory receptors and they become a part of you. You only smell like decomposition now because your skin and hair and clothes and respiratory system are coated in bits of the victims."

John fought another unpleasant lurch. "Christ, Sherlock, why would you say that? Fine, I'll use the damn soap. You need a shower too - I'll be fast."

* * *

One hour, two cups of tea, and a very long shower (with the special soap) later, John felt much more human. And he kept finding his train of thought going back to Sherlock's earlier comments about there being _uses_ for not having a gag reflex. He desperately wanted to dismiss the comment as having nothing to do with anything - surely Sherlock would have come up with a dozen ways his lack of a gag reflex made him superior to mere mortals, and none of them would have had anything to do with sucking another man's cock. But John would be damned if he could think of a single other plus - now he had the image of Sherlock in his head, and it wasn't going away.

Sherlock looked downright elegant in his navy blue robe, sulking around the flat with his hair all wild and still damp. It wasn't making anything easier. John glowered at his laptop and prayed Sherlock wasn't in a deducing mood - it was one thing to be involuntarily fantasizing about your flatmate, but it was entirely another for that flatmate to know about it.

"You're stuck on it," Sherlock said suddenly.

John looked up, trying to keep the guilt off his face.

"My medical abnormality really bothers you that much? I had rather hoped you wouldn't feel the need to lecture me about it - I _have_ had specialists investigate it in the past, you know. It's not some unattended symptom in need of analyzing."

John shook his head. "Sorry - I'm not lecturing. Just - disbelief, I guess."

Sherlock let out an exasperated huff. "Fine. A demonstration." He disappeared into the kitchen.

"No, please, you don't have to -"

Sherlock reappeared holding a wooden spoon - John vaguely remembered leaving it in the drying rack the night before. It was a largish one, close to the length of John's forearm and with a handle the diameter of his thumb.

"Observe." And Sherlock tilted his head back and practically _dropped_ the spoon down his throat. He held it there for several seconds, then reached into his mouth to fish out the flat end and extract the length inch by inch.

John's trousers were suddenly too tight. Sherlock returned the spoon to the kitchen, dumping it in the sink for John to wash later, and came back to prop his weight on the arm of his chair. "I used to do that in front of Mycroft to make him gag," he admitted with the hint of a smile. "He can't stand the thought of it."

"Yeah, I -" John swallowed hard. "I can't imagine why." He knew he was turning red, could feel the heat climbing up his cheeks, but if he stood up now, Sherlock would obviously notice -

"You're not disgusted," Sherlock said slowly. He stood and wandered closer to where John was carefully holding his computer over his lap on the sofa. "I assumed you'd be bothered, but you're - _oh_." His gaze dipped to John's crotch and stayed here.

"Yes, well. I'm going upstairs. Goodnight, Sherlock." John stood, turning so Sherlock couldn't see, praying his erection wasn't as obvious as it felt.

"It's barely six."

_"Goodnight, Sherlock." _And John escaped up to his room.


	2. Chapter 2

The next few days felt like some strange sort of persecution. The case wound up depressingly quickly (no mystery about it at all, to Sherlock's crushing disappointment) and thus John found himself saddled with a flatmate who was just a little bit too _present_. And who seemed determined to make John blush.

He wasn't subtle about it, either - Sherlock was seizing every opportunity possible to demonstrate his missing gag reflex. John sat curled up with his laptop in his armchair and watched out of the corner of his eye as Sherlock deep-throated another spoon, two carrots, a popsicle, a truly impressive length of the curtain rod, and, the most disturbing, a raw zucchini. Each time Sherlock would smirk and look over at John, as if he were expecting applause. And John would studiously avoid eye contact, pretending to be engrossed in his blog. He couldn't hide his immediate reaction to the zucchini, though, and Sherlock pounced on the opportunity to tease him about it.

"You're bright red, you know."

John kept his eyes on his laptop. "I know."

"And yet you think by watching me only in your peripheral vision, I won't notice you staring."

"I'm not staring, Sherlock, I'm trying to write. You persist in showing off."

"Because you like watching." Sherlock wandered over to loom directly next to John's chair, very definitely in his personal space. "You keep imagining what my throat would feel like around your cock."

John snapped his laptop shut but refused to turn around. "Only because you won't leave it alone. Honestly, Sherlock, _boundaries_. I'll get over it eventually."

"If I wanted you to get over it I would never have mentioned it in the first place." He rested his hip on the arm of the chair, right next to John's shoulder. "I thought it over and I decided I would very much like to perform oral sex on you."

John blinked.

"You're significantly larger than the mean for British males," Sherlock continued. "By a good twenty-five percent. I think it would be an interesting experience."

_That_ snapped John out of his shock and into - not anger, necessarily, but that indefinable annoyance he was getting used to after living with Sherlock for so long. "Please tell me you don't have one of Mycroft's hidden cameras in the bathroom or something."

"Oh, God, no," Sherlock said quickly. "There are things even Mycroft doesn't want to watch. But I've seen you in just your pants a few times and I can extrapolate as well as anyone. You _are_ particularly large, aren't you?"

John knew his blush was getting worse - how exactly does one answer that question? He swallowed and tried to ignore the fact that Sherlock's own cock was less than a foot from his head. "I've never measured," he finally choked out.

Sherlock made a little humming noise. "No matter. Even if your cock is of completely average dimensions, I want to feel it in my mouth. It's been way too long."

"You've done this often?"

He felt Sherlock shrug. "Used to. Haven't since you moved in." Sherlock shifted his weight, and John could feel his gaze on the top of his head. "Before you ask," Sherlock added, "yes, I have been safe about it and yes, I'm clean. I've been no more promiscuous than you have."

Since that wasn't saying very much - John's army days were filled with a long string of one- and two-night stands - John opted to keep his mouth shut.

"So may I?" Sherlock came around the chair to kneel in front of John. He took the laptop from John's slack grip and placed it carefully on the coffee table behind him, then turned back and let his hands drop casually over John's knees. "I know you're not gay, but -"

"-but very few guys, gay or straight, would turn down an offer of a blowjob," John finished. "I'm well aware." He let his gaze rest on Sherlock's upturned face, then drift to where Sherlock's long fingers were stroking him gently through the fabric of his trousers. "You've got the most singularly unromantic way of requesting sex of anyone I've ever met, you know that?"

Sherlock smirked. "So that's a yes?"

John sighed and rolled his head back to stare at the ceiling. "That's a yes, God help me."

"Excellent." Sherlock's fingers started trailing up John's thighs toward his waist. "I _have_ been thinking about this for a while."

John licked his lips, mesmerized by the feeling of the light brushes through the fabric. "How long, exactly?" he asked.

"Mmmm. Since about two months after we moved in together, and I saw you in those ratty cotton Y-fronts. The time I accidentally splashed acid on you and you had to strip down right there in the kitchen."

"So my _least_ sexy pair of pants."

"I wasn't paying attention to the pants; I was observing the bulge beneath them." Sherlock deftly unzipped John's trousers and motioned for him to lift his hips so he could slide them down to John's knees. John was wearing another pair of plain white Y-fronts underneath - not the old ratty ones, thank goodness, but nothing particularly special either. Sherlock was eyeing his pants with the glee he usually reserved for locked-room murders, though. "Christ, this is going to be fantastic. Lift your hips again."

John did, feeling absurdly self-conscious, and then he was sitting in his armchair in just his jumper while a fully-clothed Sherlock grinned at his cock with manic glee. He didn't even need to glance down to know that he was more than half hard already, and growing by the minute.

"Incredible," Sherlock murmured. "If anything, I under-estimated. You are so fucking huge - oh, this is going to be glorious. Significantly above average for girth as well as length."

"Making me a bit self-conscious, here."

"Why?" Sherlock glanced up at his face, then reverently stroked two fingertips down the length of John's cock. "I'm the one with the size kink. If anything, I'm the one who should be embarrassed."

"Yeah, well, I wasn't aware you even knew what sex _was_ until the whole gag reflex thing came up."

Sherlock shot him an incredulous look. "I may not flaunt it, John, but don't you think that would be a rather major thing for me to not know?"

"Oh, like the solar system?"

"Shut up," Sherlock said, and leaned forward to engulf John's cock with his mouth.

And _Christ_ did it feel amazing. John collapsed against the back of the armchair and didn't protest when Sherlock tugged his hips forward a bit more so John was semi-reclining with his cock jutting out obscenely. Sherlock licked gently over the head, then slid his lips all the way down the shaft again.

_"Fuck."_

Sherlock pulled off slowly, allowing the suction to build until it made a little popping noise when he slid free. "This won't work - the angle is all wrong. Come to bed."

John obeyed with a stunning lack of reservations. Sherlock led him by the hand into his room, letting go only to smooth out his bedspread over the unmade sheets and to gently shove John onto it.

"Sit up with your back against the headboard, legs apart."

John took the opportunity to shuck his jumper - surreal as this all was, it was one step too far for him to still be wearing it while Sherlock was sucking him off. Sherlock was still completely clothed, right down to his shiny expensive shoes, but he'd surely undress when he was ready . . .

Sherlock pounced on him like an oversized cat the moment John was positioned properly. He prowled up the length of the mattress until he was on all fours between John's legs and was just _breathing_ on his cock. If John hadn't been fully hard already, he would have gotten that way rather quickly. Sherlock looked up at John's face with a pure feral grin - and then he attacked.

John felt like he had just touched an electric fence - one moment he was staring into his mad flatmate's eyes, still feeling slightly stunned at the direction his life had taken, and the next moment Sherlock's mouth was all the way up against the base of his cock and _fuck_ John could feel the ring of Sherlock's throat around him as he worked John's length deeper. Sherlock pulled off with an obscene slurp and sucked in a deep breath. "Phenomenal," he growled quietly, vibrations from his voice rumbling through John's skin. "You're so thick - I have to stretch to fit all of you in. It's incredible." And he worked his way down again, using his tongue for added sensation as he slowly sank down inch by inch until John was moaning and his hips were twitching and Sherlock had to restrain him to keep him from bucking forward too forcefully.

"Slow," he gasped when he came up for air again. "Let me savor you, John."

But John didn't want to be savored, and he would have said so if his voice had been working properly. He wanted that deliciously moist heat around him again and again, sliding back and forth until he couldn't hold back anymore. He wanted to come in Sherlock's mouth, pouring his come straight down Sherlock's throat so Sherlock wouldn't have a chance to draw back or spit it out. He wanted to wrap his fingers in Sherlock's curls and fuck himself with those talented lips and tongue and bruise Sherlock's goddamned uvula. Three days ago John hadn't known he would want this, but now he wanted it more than fucking _breathing_.

And Sherlock, damn his perceptiveness, seemed to realize it. He licked his lips slowly, eyes stuttering back and forth from John's face to his cock, and then seemed to make a decision. And fitted his mouth and throat over John tigher than a fucking glove.

"Fuck, Sherlock, I can't - I just -"

Sherlock hummed around him, ratcheting the tension inside John even higher. It was a vaguely encouraging hum, accentuated by how Sherlock's hand had just moved from tracing the inside of John's thigh and now was massaging his bollocks in time with Sherlock's tongue movements against John's shaft. And suddenly John couldn't take anymore, and the world went fuzzy a bit around the edges and he was pouring his come into Sherlock exactly like he had been dreaming about. Sherlock hummed again, a happy noise, and waited until John's body had stopped jerking before carefully pulling away from his cock and crawling up and laying his head on John's chest.

"You're still hard," John observed once he got his breath back and the world had stopped spinning.

Sherlock shifted slightly and pressed a kiss to John's collarbone. "Give me your hand and you can help."

John obligingly let his hand flop, palm-up, on his stomach. Sherlock yanked down his trousers and pants with no sign of his earlier finesse and grabbed John's wrist to press his hand over his own straining erection. John let his fingers curl posessively over Sherlock's warm skin. Sherlock covered John's hand with his own and set up a punishing rhythm - before long, he was groaning and then spilling over their joined hands and eventually slumped back, as boneless as John felt, against John's shoulder once again.

"So." John said quietly. "That happened."

"Finally," Sherlock mumbled.

John tried to twist his head a bit so he could see Sherlock's face, but all he got was a mouthful of dark curls. "You really - that was okay?"

Sherlock tightened the arm thrown over John's ribs and burrowed deeper against John's side. "Knew you'd be amazing. Didn't want to push."

" . . . because you didn't want to scare me away."

John felt Sherlock nod.

"I'm not leaving you, Sherlock. When are you going to realize that?"

Sherlock made a low, sleepy noise. "Everyone leaves. Eventually. Don't want to let you go."

John wrapped his free arm around Sherlock's shoulders and pressed a kiss into his hair. "I'm not going anywhere. You don't have to hide from me."

"I won't change. Can't."

"I don't want you to." John nuzzled another kiss into Sherlock's curls. "I'm happy just the way we are, strange experiments and all. Although the sex will definitely be a plus."

"Mmmmm."

"Sherlock?"

But there was no answer, because Sherlock was asleep. John let his cheek rest against the top of Sherlock's head and eventually drifted off.


End file.
